Topical skin barrier

ABSTRACT

A topical skin barrier for protecting and promoting healing of skin, and for providing comfort to a patient, comprises a semi-solid hydrocarbon and a water-absorbing compound. The topical skin barrier effectively adheres to skin, affords protection from moisture and waste, and provides transparency in use. Methods of in vitro evaluation are for (i) a composition&#39;s protection from moisture and waste, and (ii) a composition&#39;s adhesion to skin.

FIELD OF THE INVENTION

The present invention relates generally to topical skin barriers andtheir evaluation methods. The invention relates specifically to topicalskin barriers for protecting and promoting healing of patients' skin,and for providing comfort to patients. The invention also relatesspecifically to in vitro methods of evaluating the efficacy of topicalskin barriers in protecting patients' skin from moisture and waste, andin their adhesion to skin.

BACKGROUND OF THE INVENTION

Topical skin barrier compositions, hereinafter referred to as “topicalskin barriers”, are known in the medical arts. Topical skin barriershave been used, inter alia, for the treatment of bedridden patients'skin where irritation from moisture, urine, diarrhea, feces, enzymaticdrainage, exudate, dust, dirt, and the like (hereinafter, collectively,“moisture and waste”) is problematic, painful, and unfortunatelycommonplace. Patients' skin, regardless of being intact or non-intact,ideally needs to be protected from moisture and waste to prevent skinbreakdown, promote healing, and provide comfort.

Ultimately it is the role of topical skin barriers to protect skinexposed to moisture and waste, since enzymes present in waste canquickly lead to skin breakdown. While any topical skin barrier thatprotects skin from exposure to moisture and waste, acting as a barriertherefrom, may be beneficial, an ability to remain adhered to bothintact and non-intact skin is obviously critical to satisfactoryperformance. Furthermore, known topical skin barriers are oftensubstantially opaque after application to skin which does not allow thecondition of the skin to be visually assessed. This can lead to aperceived need to aggressively remove selected portions of the topicalskin barrier to visually inspect the skin thereunder; such aggressiveremoval, in turn, can lead to further injury to the skin.

An example of a known topical skin barrier is disclosed in U.S. Pat.Applic. Pub. No. 2003/0091540 titled “Compositions and Methods forDelivering Antibacterial, Antifungal and Antiviral Ointments to theOral, Nasal or Vaginal Cavity”. Disclosed therein are ointments andmethods for treating oral and vaginal fungal and yeast infections.Another is disclosed in U.S. Pat. No. 6,849,277 titled “Composition forMoist Skin”. Therein, a composition for treating skin in the presence ofexcessive moisture is an ointment or paste including zinc oxide, afungicide, a bactericide, and water-absorbing macromolecular materialsin a water-immiscible vehicle.

Although the known compositions have provided, to some degree,acceptable adhesion and barrier properties, they have however beeninadequate in several respects. These inadequacies include limitationsto certain applications rather than for the skin in general (e.g., theaforecited Pub. No. 2003/0091540) and requirement of a bactericide and abase cream containing water (e.g., the aforecited U.S. Pat. No.6,849,277). Perhaps even more importantly, known compositions haveheretofore not been sufficiently transparent to permit visualinspection.

Therefore, there has existed a long-felt need for a substantiallytransparent, anhydrous, topical skin barrier for general skin care whichis not limited in application to a specific area of a patient's body.Such a product would also optionally include antifungal properties. Thetopical skin barrier would need to adhere well to skin and provide agood barrier in an environment of moisture and waste. Moreover, it wouldbe desirable for such a product to have “detectable transparency”,thereby rendering it detectable to an observer while being substantiallytransparent to permit visual observation of the skin thereunder. Therehas also existed a long-felt need for a relatively simple and effectivein vitro method of evaluating the efficacy of topical skin barriers inprotecting patients' skin from moisture and waste, and in their adhesionto skin.

SUMMARY OF THE INVENTION

An object of the present invention is to provide a substantiallytransparent, anhydrous, topical skin barrier for general skin care whichis not limited in application to a specific area of a patient's body.

Another object of the present invention is to provide a substantiallytransparent, anhydrous, topical skin barrier for general skin care whichoptionally includes an antifungal property.

An additional object of the present invention is to provide asubstantially transparent, anhydrous, topical skin barrier for generalskin care which adheres well to skin and provides a good barrier in anenvironment of moisture and waste.

A further object of the present invention is to provide a substantiallytransparent, anhydrous, topical skin barrier for general skin care whichhas detectable transparency.

A yet further object of the present invention is to provide a relativelysimple and effective in vitro method of evaluating the efficacy oftopical skin barriers in protecting patients' skin from moisture andwaste, and in their adhesion to skin.

In accordance with basic aspects of the present invention, a topicalskin barrier for protecting and promoting healing of skin, and forproviding comfort to a patient, comprises a semi-solid hydrocarbon and awater-absorbing compound. The topical skin barrier effectively adheresto skin, affords protection from moisture and waste, and providestransparency in use. Further in accordance with the invention aremethods of in vitro evaluation of (i) a composition's protection frommoisture and waste, and (ii) a composition's adhesion to skin.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an illustration of a method for evaluating the efficacy oftopical skin barriers in protecting patients' skin from moisture andwaste, being prepared for use in accordance with the present invention.

FIG. 2 is a depiction of the method of FIG. 1 during use.

DETAILED DESCRIPTION OF THE INVENTION

As used here throughout, the term “water-absorbing compound” is intendedto include any suitable compound such as, for example, (i) cellulosegum, whether identified as water-absorbing or otherwise, (ii)carboxymethylcellulose, commonly referred to as “CMC” and which iscommercially available, for example, as BLANOSE® brand water solublepolymer from Hercules Incorporated of Wilmington, Del., (iii) karayagum, and even (iv) specific brands of superabsorbent polymers such asWATER LOCK® G-430 and WATER LOCK® A-240, each being commerciallyavailable from Grain Processing Corporation of Muscatine, Iowa. Also asused here throughout, the terms “synthetic urine” or “suitable liquid”in the context of evaluation are intended to include any suitable liquidhaving properties similar to human urine such as, for example, URISUB™synthetic urine for testing purposes from CST Technologies, Inc. ofGreat Neck, N.Y., and even a “no-rinse incontinence cleanser” such asPERI-WASH II® cleanser from Coloplast A/S of Denmark.

In development of the topical skin barriers of the present invention,several experimental compositions were formulated. These are presentedas the following Examples 1-10.

Example 1

25.0 grams of karaya gum is added to 74.5 grams of melted petrolatum.The two are mixed with a spatula. 0.5 grams of tocopheryl acetate isadded and the mixture is spatulated and cooled to room temperature. Thismixture adheres well in the presence of synthetic urine and provides agood barrier to moisture. However, the mixture is dark in color due tothe karaya gum.

Example 2

25.0 grams of cellulose gum is added to 74.5 grams of melted petrolatum.The two are mixed with a spatula. 0.5 grams of tocopheryl acetate isadded and the mixture is spatulated and cooled to room temperature. Thismixture adheres well in the presence of synthetic urine and provides abetter moisture barrier than example 1. The mixture is lighter in colorthan example 1 but is still slightly dark.

Example 3

25.0 grams of WATER LOCK® G-430 superabsorbent polymer is added to 74.5grams of melted petrolatum. The two are mixed with a spatula. 0.5 gramsof tocopheryl acetate is added and the mixture is spatulated and cooledto room temperature. This mixture does not adhere well in the presenceof synthetic urine.

Example 4

25.0 grams of WATER LOCK® A-240 superabsorbent polymer is added to 74.5grams of melted petrolatum. The two are mixed with a spatula. 0.5 gramsof tocopheryl acetate is added and the mixture is spatulated and cooledto room temperature. This mixture does not adhere well in the presenceof synthetic urine.

Example 5

25.0 grams of cellulose gum is added to 74.0 grams of melted petrolatum.The two are mixed with a spatula. 1.0 gram of zinc oxide is added andthe mixture is spatulated and cooled to room temperature. This mixtureadheres well in the presence of synthetic urine and provides a goodmoisture barrier. The color is more appealing than examples 1 or 2.

Example 6

25.0 grams of cellulose gum is added to 73.0 grams of melted petrolatum.The two are mixed with a spatula. 2.0 grams of dimethicone is added andthe mixture is spatulated and cooled to room temperature. This mixtureadheres well in the presence of synthetic urine and provides a goodmoisture barrier. The dimethicone gives a mixture that is easier tospread.

Example 7

25.0 grams of cellulose gum is added to 72.0 grams of melted petrolatum.The two are mixed with a spatula. 1.0 gram of zinc oxide and 2.0 gramsof dimethicone are added and the mixture is spatulated and cooled toroom temperature. This mixture adheres well in the presence of syntheticurine and provides a good moisture barrier. It is easy to spread and hasan appealing color.

Example 8

25.0 grams of cellulose gum is added to 72.5 grams of melted petrolatum.The two are mixed with a spatula. 0.5 grams of tocopheryl acetate and1.0 gram of dimethicone are added and the mixture is spatulated andcooled to room temperature. This mixture adheres well in the presence ofsynthetic urine and provides a good moisture barrier. It is easy tospread.

Example 9

25.0 grams of cellulose gum is added to 73.5 grams of melted petrolatum.The two are mixed with a spatula. 1.0 gram of zinc oxide and 0.5 gram oftocopheryl acetate are added and the mixture is spatulated and cooled toroom temperature. This mixture adheres well in the presence of syntheticurine and provides a good moisture barrier. It has an appealing color.

Example 10

25.0 grams of cellulose gum is added to 71.5 grams of melted petrolatum.The two are mixed with a spatula. 1.0 gram of zinc oxide, 0.5 gram oftocopheryl acetate, and 2.0 grams of dimethicone are added and themixture is spatulated and cooled to room temperature. This mixtureadheres well in the presence of synthetic urine and provides a goodmoisture barrier. It is easy to spread and has an appealing color.

The foregoing examples are presented in tabular form as follows (amountsare expressed in grams):

Ex. 1 Ex. 2 Ex. 3 Ex. 4 Petrolatum 74.5 74.5 74.5 74.5 Karaya gum 25.0 —— — Cellulose gum — 25.0 — — WATER LOCK ® G-430 — — 25.0 — Tocopherylacetate  0.5  0.5  0.5  0.5 WATER LOCK ® A-240 — — — 25.0 Ex. 5 Ex. 6Ex. 7 Petrolatum 74.0 73.0 72.0 Cellulose gum 25.0 25.0 25.0 Zinc oxide 1.0 —  1.0 Dimethicone —  2.0  2.0 Ex. 8 Ex. 9 Ex. 10 Petrolatum 72.573.5 71.5 Cellulose gum 25.0 25.0 25.0 Tocopheryl acetate  0.5  0.5  0.5Dimethicone  2.0 —  2.0 Zinc oxide —  1.0  1.0

It is to be understood that the foregoing Examples 1-4 have beenpresented as test results in development of the instant invention, whileExamples 5-10 specifically serve as preferred or exemplary embodimentsof the invention. Also, the phrase “appealing color” in the examples isintended to mean an appealing or subjectively aesthetic quality;additionally, “appealing color” is intended to include “detectabletransparency” as aforementioned.

It is to be appreciated from the foregoing disclosure that the presentinvention satisfies the long-felt needs for a substantially transparent,anhydrous, topical skin barrier for general skin care which (i) is notlimited in application to a specific area of a patient's body, (ii) mayoptionally include an antifungal, (iii) adheres well to skin andprovides a good barrier in an environment of moisture and waste, and(iv) has detectable transparency. The present invention, therefore, maybe further characterized, for example, as performing at least assatisfactorily as the prior CRITIC-AID® Paste from Coloplast A/S ofDenmark.

Although not presented in Examples 1-10 above, further discoveries havebeen made relative to development of an antifungal property in thetopical skin barriers of the present invention. The addition of asuitable antifungal, such as, for example, miconazole nitrate orclotrimazole, is desirable in some instances because the aforedescribedskin maladies are often susceptible to fungal infections. In thisregard, it has been further discovered that such addition of a suitableantifungal gives an unexpected, additional result of an enhancedmoisture and waste barrier property in a given formulation of thepresent invention. In a preferred, exemplary embodiment, utilization ofmiconazole nitrate in a range by weight from about 1.5% to about 2.5%alleviates a need for a material (e.g., zinc oxide) which lightens acoloration appearance of a given formulation. As an alternativeclotrimazole may be substituted for miconazole nitrate, in a range byweight from about 0.5% to about 2.0%. Specifically, it has been foundthat the addition of miconazole nitrate or clotrimazole in suchproportions inherently provides an appealing subjectively aestheticquality along with detectable transparency.

In development of further preferred or exemplary embodiments of thepresent invention, it was recognized that utilization of an antifungaloften occurs in an unpleasant odor-producing fungal environment.Therefore, it may be desirable to add an odor control agent to a givenformulation of the invention, in a range by weight from about 0.1% toabout 10.0%. A suitable odor control agent could be virtually anycompatible, commercially available fragrance or deodorizer such as, forexample, ORDENONE® brand deodorizer from Belle-Aire Fragrances, Inc., ofMundelein, Ill.

Turning, now, to FIGS. 1 and 2, there shown is a exemplary in vitromethod of evaluating the efficacy of topical skin barriers in protectingskin from moisture and waste, further in accordance with the presentinvention. The method was developed in response to rather complexevaluation protocols involving, for example, rolled filter paper asdisclosed in Shah, et al., Evaluation of Moisture Penetration ThroughSkin Protectant Barriers by Paper Chromatography, Adv. Wound Care p.20-21, 25, and 27 (July-August, 1995).

In general, testing has shown that an understanding of barrierproperties of compositions may be gained from such simple devices asfilter material, a synthetic urine bath, and a stopwatch. For instance,a small amount of a selected composition can be coated onto the filtermaterial and immersed directly into a bath for a specified period oftime. Many prototypes can be studied by this simple method to establishoptimum moisture and waste barrier properties. In a specific exemplaryembodiment of such an in vitro method of evaluating protection frommoisture and waste, and with particular reference to FIG. 1, filtermaterial 10 is cut into strips (A-D, as shown) measuring about 5.25″ byabout 0.50″. The “filter material” may be any suitable filter paper suchas, for example, WHATMAN® brand #4 filter paper from Whatman PaperLimited of the United Kingdom. Using a pencil, a line is drawn about0.50″ from the material's bottom edge (at 15). A small hole 25 is madenear a top center portion of the strip of material 10. Hole 25 isprovided to hang the strip on a horizontally-positionable string S overa suitable liquid serving as synthetic urine bath B by way of posts P. Adot 30 of water soluble ink is then placed just above line 15, which isutilized in tracking moisture migration as will be described. Each stripA-D of material 10 is then evenly coated on both sides thereof with,respectively, approximately 0.1 g. of a separate topical skin barrier tobe respectively evaluated (as shown, TSB(1)-TSB(4)). Each coatingcorresponds, as shown, to a portion of material 10 between line 15 andits bottom edge. With each strip A-D of material 10 so prepared, theyare then suspended from string S via hangers H at holes 25 so thattopical skin barriers TSB(1)-(4) may be simultaneously, or nearly so,submerged in bath B of synthetic urine at a temperature of about 25 C byway of lowering string S at each post P. In this manner, it is to beappreciated that each strip A-D of filter material 10 including therespective coatings of barriers TSB(1)-(4) may be maintained at aselected depth in bath B not to exceed lines 15. Strips A-D aremaintained in such immersed positions for about 2 hours. As shown inFIG. 2, it can be helpful to monitor the progress of the synthetic urinemigrating up strips A-D with respect to lines 15 at intermediate elapsedtimes (e.g., 30 minutes and 1 hour, etc.). After about 2 hours stripsA-D are removed from bath B. Respective distances of moisture migrationas evidenced by an extent of vertical transport of ink from dot 30, upeach strip of filter material 10 relative to lines 15, are thenmeasured. Those of ordinary skill in the art will appreciate that suchdistances are indicative of the efficacy of the respective topical skinbarriers in protecting skin from moisture and waste, and may beconveniently expressed as a rate of penetration in mm/2 hr. Of course,the aforedescribed evaluation method may be carried out with virtuallyany number of strips A-(N) of material 10, for, respectively, any numberof different topical skin barriers TSB(1)-(N) to be evaluated withrespect to one another.

Finally, although not specifically illustrated but with analogouscontinued reference to the drawings, the present invention also providesan in vitro method of evaluating the efficacy of topical skin barriersin their adhesion to skin. This evaluation method, in accordance withanother aspect of the present invention, shows that as in theaforedescribed barrier property evaluation, an understanding of efficacyof adhesion in a particular topical skin barrier may be gained fromutilization of simple devices. In this method, a stainless steel plateis substituted for each strip of material 10, and bath B is provided asa sonication bath of synthetic urine (i.e., a bath of synthetic urineintentionally agitated by way of ultrasonic waves. Using a suitablemarker, a line is drawn about 4 cm. from the plate's bottom edge. Asmall hole is made near a top center portion of the plate, with the holeproviding means to hang the plate on a horizontally-positionable stringover the sonication bath by way of posts. Each plate is then evenlycoated on one side thereof with, respectively, approximately 1.0 g. of aseparate topical skin barrier to be respectively evaluated,corresponding to a portion of the plate between the line and its bottomedge. Each plate is then suspended from the string via a hanger engagingthe hole so that a given topical skin barrier coated on each plate maybe simultaneously, or nearly so, submerged in the sonication bath ofsynthetic urine at a temperature of about 25 C by way of lowering thestring as aforedescribed. In this manner, it is to be appreciated thateach plate including the respective topical skin barrier coatings areequally maintained at a selected depth in the bath exceeding the linesdrawn on each plate. The plates are maintained in such immersedpositions for about 5 minutes, at which time they are removed from thebath and respective adhesions of the various topical skin barriers arecompared to one another. Those of ordinary skill in the art willappreciate that such comparisons are indicative of the efficacy of thetopical skin barriers to remain adhered to skin in a dynamic patientenvironment where the presence of moisture and waste is typical. Ofcourse, as with the aforedescribed barrier evaluation method, thisadhesion evaluation method may be carried out with any number of platesfor, respectively, any number of different topical skin barriers to beevaluated with respect to one another.

From the aforedescribed evaluation methods of the present invention, itwas found that moisture and waste barrier properties, and also adhesionproperties, were noticeably affected by incorporation of semi-solidhydrocarbon and cellulose gum as apparent by study of the foregoingExamples 1-10. In addition, it was discovered that a specific type ofcellulose gum is critical to performance of the topical skin barriers ofthe present invention, with a combination of petrolatum and specificgrades of cellulose gum providing desired barrier and adhesionproperties better than other combinations. In particular, an optimumcellulose gum has a “degree of substitution” of 0.80-0.95 and a “fine”particle size. Generally, a lower degree of substitution results inbetter moisture absorption and hence better adhesion; however, too low adegree of substitution actually absorbs moisture too well and therebydegrades adhesion.

While the present invention has been particularly shown and describedwith reference to the accompanying figures and specification, it will beunderstood however that other modifications thereto are of coursepossible; and all of which are intended to be within the true spirit andscope of the present invention. It should be appreciated thatcomponents, dimensions, elapsed times, and other particulars ofexemplary embodiments of the invention aforedescribed may be substitutedfor others which are suitable for achieving desired results, or thatvarious accessories may be added thereto. It is also to be understood ingeneral that any suitable alternatives may be employed to provide thetopical skin barriers and their evaluation methods of the presentinvention.

Lastly, of course, the choice of compositions, sizes, and strengths ofvarious aforementioned elements of the products and methods of thepresent invention are all a matter of design choice depending uponintended uses thereof.

Accordingly, these and other various changes or modifications in formand detail of the present invention may also be made therein, againwithout departing from the true spirit and scope of the invention asdefined by the appended claims.

What is claimed is:
 1. A topical skin barrier comprising: a semi-solidhydrocarbon provided in a range by weight from about 25.0% to about90.0%; and a cellulose gum provided in a range by weight from about 5.0%to about 75.0%, the cellulose gum having a degree of substitutionbetween 0.80-0.95.
 2. The topical skin barrier of claim 1, wherein thesemi-solid hydrocarbon is petrolatum.
 3. The topical skin barrier ofclaim 2, wherein the petrolatum is white petrolatum.
 4. The topical skinbarrier of claim 1, wherein the cellulose gum is carboxymethylcellulose.5. The topical skin barrier of claim 1, further comprising: zinc oxideadded to the topical skin barrier.
 6. The topical skin barrier of claim1, further comprising: tocopheryl acetate provided in a range by weightfrom about 0.1% to about 5.0%.
 7. The topical skin barrier of claim 1,further comprising: dimethicone provided in a range by weight from about0.1% to about 20.0%.
 8. The topical skin barrier of claim 1, furthercomprising: miconazole nitrate added to the topical skin barrier.
 9. Thetopical skin barrier of claim 1, further comprising: clotrimazole addedto the topical skin barrier.
 10. The topical skin barrier of claim 1,further comprising: an antifungal agent provided in a range by weightfrom about 0.5% to about 2.5%.
 11. A topical skin barrier comprising: asemi-solid hydrocarbon provided in a range by weight from about 25.0% toabout 90.0%; tocopheryl acetate provided in a range by weight from about0.1% to about 5.0%; and a cellulose gum provided in a range by weightfrom about 5.0% to about 75.0%, the cellulose gum having a degree ofsubstitution between 0.80-0.95.